This invention relates to a cutting insert of the "on-edge" type and having selectively usable cutting edges each adapted to be brought into active cutting position when the insert is indexed. The advantages of an "on-edge" indexable insert of the same general type as the present insert are discussed in detail in Striegl U.S. Pat. No. 4,182,587.
The insert of the present invention is especially useful as the front insert of an end milling cutter. When so used, the insert is disposed within a pocket in the forward end portion of the cutter body and seats against a locator at the rear of the pocket.
In some cases, it is necessary that the front insert of an end mill make a radiused cut in the workpiece rather than a right-angled or sharp-cornered cut. In order to effect a radiused cut, it is necessary to form the insert such that the tip of its cutting edge is convexly curved. Difficulty has been encountered, however, in providing a comparatively thin insert, and particularly a comparatively thin, on-edge insert, having multiple cutting tips each curved on a relatively large radius. If each cutting tip of such an insert is radiused by conventional techniques, the curvature of the inactive rear end of the insert prevents the insert from seating intimately against the locator at the rear of the insert pocket. As a result, thin inserts having cutting tips curved on a relatively large radius generally have been designed in the past with only a single cutting tip and with a flat and planar non-cutting rear end capable of seating against the locator.